Traditionally, there has been a multiband built-in antenna including a power feeding unit composed of a feeding pin coupled to an external circuit and a feeding line having a predetermined length and including an end coupled to the feeding pin, and a radiating patch separated by a predetermined gap from the power feeding unit via a space, coupled to a portion of the power feeding unit, and configured to induce a current supplied from the power feeding unit. The multiband built-in antenna further includes a short-circuit unit having an end coupled to the radiating patch and another end grounded (refer to, for example, Japanese Laid-open Patent Publication No. 2003-318640).
Other examples of related art are Japanese Laid-open Patent Publication Nos. 2002-314330, 2013-021716, and 2007-300398.